Shock absorber for adjustable optical components

ABSTRACT

A hydraulic or pneumatic bumper is interposed between a slidable lens assembly and a support therefor to cushion the impact in a terminal position of the displacement stroke.

United States Patent [72] Inventors Lothm-Kirstein Bad Kreuznach; GerdKunz, Biebelsbeim, both of, Germany [21] Appl. No 810,639 [22] FiledMar. 26, 1969 [45] Patented July 20, 1971 [73] Assignee Fa. Joe.Schneider & Co., Optische Werke Kreumach, Bad Kreumach, Germany [32]Priority Apr. 4., 1968 [33] Germany [31] P 17 72142.5

[S4] SHOCK ABSORBER FOR ADJUSTABLE OPTICAL COMPONENTS 1 Claim, 4 DrawingFigs.

[52] US. Cl 350/255, 350/187 [51] Int. Cl G02b 7/04 50 Field of Search I350/41, 42, 44, 187, 255, 310,40, 46,47; 95/125, 45, 46; 267/65; 188/87,94; 74/27; 355/62, 63

[56] References Cited UNITED STATES PATENTS 552,006 12/1895 Runkel188/94 UX 756,881 4/1904 Nehring 95/45 2,572,919 10/1951 French et al..95/125 UX 2,851,924 9/1958 Beusker 350/255 2,906,185 9/1959 Naumann etal. -95/45 X 2,506,947 5/1950 Walker 350/187 2,540,017 1/1951 Thompson355/63 X Primary Examiner-David H. Rubin Attorney-Karl F. Ross ABSTRACT:A hydraulic or pneumatic bumper is interposed between a slidable lensassembly and a support therefor to cushion the impact in a terminalposition of the displacement stroke.

PATENTEU JUL20 :97:

III iwllwlllll Fig.3

Lofhar Kirsfein Gerd Kurz Inventors.

" Attorney SHOCK ABSORBER FOR ADJUSTABLE OPTICAL COMPONENTS Our presentinvention relates to an optical system wherein an objective or a partthereof is displaceably mounted on a support that is to be movablebetween two limiting positions.

The displacement (particularly in axial direction) of one or more lensesof an optical system is used to very the effective focal lens of azoom-type objective and/or to select the range. In small cameras, thisadjustment of an objective component generally does not give rise toobjectionable impact objectionable impact so that a padding of cork,rubber or other elastic material will sufficiently damp the shock as themobile parts strike a fixed step. In the case of larger equipment,however, e.g. as used in television cameras, this is no longer trueinasmuch as the mobile masses are heavy enough to generate appreciableshocks which could damage the sensitive optical elements.

It is, therefore, the general object of our invention to provide meansin such optical system for effective cushioning the impact of tworelatively movable parts in order to prevent possible dislocations.

The use of conventional dashpot assemblies in a shock absorber of thisnature is not practical since optical components frequently must beadjusted quite rapidly in either direction. It is, therefore, a moreparticular object of our invention to provide means effective only in aterminal phase of displacement to retard the advance of the mobile unittoward its limiting position.

These objects are realized, pursuant to our present invention, by theinterposition of a shock absorber including a fluid cushion between apart of the movable lens assembly and a part of its support, the fluidcushion becoming effective only in a terminal phase ofthe displacementstroke.

Although, in principle, the working fluid of the shock absorber could beeither a hydraulic liquid or a gas, the use of gases-especially air-isparticularly advantageous in order not to encumber the system.

More specifically, the cushion-forming air may be trapped in a chambercommunicating with the outer atmosphere through a vent or otherrestricted passage through which the air, on contraction, may slowlyescape and which in turn allows the air to re-enter upon reversal ofmotion. Thus, according to an advantageous embodiment, the chamber maybe formed by an open-ended cylinder and a piston on two relativelymovable parts, the piston being normally withdrawn from the cylinder butfitting into its-open end with small clearance as the two parts approachclose to each other. The chamber could also be formed by a flexible,preferably resilient envelope which may be traversed by a guide rail inan incompletely fluidtight manner so that its interior can limitedlycommunicate with the outer atmosphere.

The above and other features of our invention will be described ingreater detail hereinafter with reference to the accompanying drawing inwhich:

FIG. 1 illustrates, partly in side elevation and partly in axialsection, a camera objective provided with shock absorber means embodyingthe invention; and

FIGS. 24 are sectional detail views illustrating several modificationsof the system of FIG. 1.

In FIG. I we have illustrated a camera housing 1 whose bottom forms awell 3 spanned by several parallel guide rails 9 (only one shown) onwhich a lens carrier 2 is slidably supported. Carrier 2 has extensions11, 11', the first one forming a seat for ball bearings 12 engaging therails 9 whereas the second one supports pistons 4 individuallystraddling these rails, each piston confronting an open-ended cylinder 5on a stationary rib 7 traversed by the rails 9. A boss 6 inside cylinder5 defines therewith a ring channel adapted to receive an annular face ofthe corresponding piston 4 with small peripheral clearance whereby theair in that space is compressed as the part 22 approaches the rib 7. Aflange 8 on piston 4 limits the penetration of a small residual airpocket therein which facilitates the subsequent separation of the piston4 from the cylinder 5.

In the operation of the system of FIG. 1, which may be part of atelevision camera, the lens carrier 2 can be axially displaced along therails 9 and can be locked, by conventional clamps or the like not shown,in a selected position. If, upon release of these clamps, the camerashould be tilted forwardly, the carrier 2 will tend to slide toward theleft, yet the impact of the approach of extensions 11, 11' to theirrespective stops 21, 7 will be cushioned by the interengagement ofpistons 4 and cylinders 5. Naturally, a similar shock absorber may beeffective in the other limiting position of the lens carrier 2; for thispurpose, one or more duplicates of piston 4 and cylinder 5 could bemounted, for example, on extension 11 and rib 7, respectively, inconfronting relationship.

FIG. 2 shows generally the same system wherein, however, thepiston-and-cylinder assembly of FIG. 1 has been replaced by a bellows 13on rib 7. The bellows 13 is traversed by the rail 9 with enoughclearance to allow its interior to communicate, to a restricted extent,with the outside air. After the lower end of carrier extension 11 hascompressed the bellows 13, the carrier can freely move in the oppositedirection (i.e. to the right) whereupon the bellows gradually re-expandspreparatorily to a further reversal of motion.

In FIG. 3 the bellows 13 has been replaced by a spherical envelope orball 14 which, again, may have some communication with the surroundingatmosphere at the points of traverse of rail 9. Naturally, there may bean individual bellows 13 or ball 14 mounted on each rail 9.

In FIG. 4, finally, a resilient cup 15 similar to conventional suctioncups has been mounted on the carrier extension 11 to confront a flatsurface of rib 7; this cup is not traversed by a rail 9 but may bedisposed between two parallel rails. In order to allow for the escape ofair from the interior of the cup in its contacting position, and for thereentry of air upon reversal of the motion of carrier 2 (FlGnl), a smallvent hole 15 is formed in its wall.

We claim:

1. In an optical system including a lens support with a rail parallel toan optical axis and lens means having a part slidably guided by saidrail for displacement between two limiting positions, the combinationtherewith of shock absorber means including a cylinder member with anopen end and a piston member coaxial therewith confronting said openend, one of said members being mounted on said guided part with its axisparallel to the direction of displacement, the other of said membersbeing mounted on a part of said support and being spaced from the otherof said members during a major portion of a displacement stroke betweensaid limiting positions, said piston member entering the open end ofsaid cylinder member upon said lens approaching one of said limitingpositions and being receivable in said open end with small clearance forcushioning the terminal movement of the lens by compressing the airtrapped in said cylinder member, said piston member and said cylindermember being axially traversed by said rail, said cylinder member havinga central boss hugging said rail and defining with the cylinder wall aring channel, said piston member having an annular face spaced from saidrail and receivable in said ring channel.

1. In an optical system including a lens support with a rail parallel toan optical axis and lens means having a part slidably guided by saidrail for displacement between two limiting positions, the combinationtherewith of shock absorber means including a cylinder member with anopen end and a piston member coaxial therewith confronting said openend, one of said members being mounted on said guided part with its axisparallel to the direction of displacement, the other of said membersbeing mounted on a part of said support and being spaced from the otherof said members during a major portion of a displacement stroke betweensaid limiting positions, said piston member entering the open end ofsaid cylinder member upon said lens approaching one of said limitingpositions and being receivable in said open end with small clearance forcushioniNg the terminal movement of the lens by compressing the airtrapped in said cylinder member, said piston member and said cylindermember being axially traversed by said rail, said cylinder member havinga central boss hugging said rail and defining with the cylinder wall aring channel, said piston member having an annular face spaced from saidrail and receivable in said ring channel.